Many downhole tools are operated with hydraulic pressure delivered from the surface through a control line that runs along on the outside of a tubing string. One typical application is a sub surface safety valve. At times such valves fail and another valve is delivered on top to replace the defective safety valve. However, in order to make the replacement operate, access to the control system for the original valve had to be provided for the replacement valve. This was accomplished using an annular chamber that was formed within a pin and box connection providing a short length of circumferential thin wall through which a perforating tool had to penetrate for access to the control system. Such designs are illustrated in U.S. Pat. No. 5,496,044; 5,799,949 and 6,260,850. The problem with this design is the short height of the annular chamber, about ½ inch long, required the penetrating tool to be specifically placed on a locating shoulder so the penetrating device would go through at a precise location aligned with the annular chamber. Many times with the well containing contaminants such as paraffin or other debris, it was difficult to properly land the penetrating tool in the proper position to strike through the tubular wall and into the annular chamber. This condition is described in conjunction with subsurface safety valves but is applicable to a variety of downhole tools that need pressure access to a chamber to operate the tool in some way. For example, a production string packer has used the annular chamber described in the patents above to pressurize a piston to release the set of the packer. Other downhole tool applications are contemplated for this access issue through the production tubing.
The present invention allows access through the tubing into a much longer annular chamber that is now disposed along a joint in the tubing string and no longer tied to the short space available within a pin and box connection, as in the past. As a result, a specific landing shoulder is no longer required and the target range for penetration has been increased from about ½ inch to lengths over 1 inch to lengths of 6-10 feet or longer. These and other advantages of the present invention will be more apparent to those skilled in the art from a review of the description of the preferred embodiment and the drawings which appear below with the appended claims defining the full scope of the invention.